Reading ISN code is for key programming and writing ISN code is for engine control module replacement. In this post we will show a guide to read and write ISN for BMW chassis E series using Autel MK808TS, please note that this device can’t read ISN code from every BMW, need to check the device prompt.


1. Read ISN code

Step 1: Connect Autel MK808TS with car via OBD port, enter car model “BMW”, select “system mode”.

Step 2: Choose “engine system”, ensure the engine is turned off.

Step 3: Identified the current engine model, enter the engine system….

Step 4: Select “read ISN”, start to read ISN, please wait…

Step 5: Read ISN success, take a photo or screenshot to record the ISN. (Some engine’s ISN may be 2 bytes which is normal)

2. Write ISN code

Step 1: In engine menu, select “write ISN”.

Step 2: There is a risk in writing the engine ISN code. The written ISN code needs to match the vehicle, otherwise some functions will not work properly. Please proceed with caution!

Step 3: After entering the ISN code that matches the vehicle correctly, click "OK" and the system will automatically write the new ISN code.

Step 4: Write engine ISN success.


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